CN110756807B

CN110756807B - Laser melting deposition method of hydrogenated titanium dehydrogenated powder

Info

Publication number: CN110756807B
Application number: CN201911201359.4A
Authority: CN
Inventors: 李晋锋; 黄留飞; 乐国敏; 刘学; 罗晋如; 刘政豪
Original assignee: Institute of Materials of CAEP
Current assignee: Institute of Materials of CAEP
Priority date: 2019-11-29
Filing date: 2019-11-29
Publication date: 2021-11-23
Anticipated expiration: 2039-11-29
Also published as: CN110756807A

Abstract

The invention relates to the technical field of metal material laser forming, and provides a laser melting deposition method of hydrogenated titanium hydride powder, which comprises the following steps: selecting irregular hydrogenated dehydrogenated titanium powder as a raw material, and spheroidizing the raw material powder; screening the spheroidized powder, and drying the screened powder in a vacuum drying oven; setting laser melting deposition process parameters and a laser scanning path; and according to the set laser melting deposition process parameters and the scanning path, under the protection of inert gas, powder is melted and deposited on the forming substrate layer by layer to prepare the titanium part. According to the invention, different laser scanning paths can be set according to requirements, so that titanium parts with different shapes can be produced; by specific laser melting deposition process parameters, the titanium part with uniform microstructure and excellent mechanical property can be prepared.

Description

Laser melting deposition method of hydrogenated titanium dehydrogenated powder

Technical Field

The invention relates to the technical field of metal material laser forming, in particular to a laser melting deposition method of hydrogenated titanium hydride powder.

Background

Titanium and titanium alloy have a series of excellent properties such as low density, high specific strength, good corrosion resistance, good ductility, good heat resistance, etc., and are widely applied to the fields of aerospace, military and national defense, vehicle engineering, etc. The metal parts prepared by the laser melting deposition method have the advantages of high material utilization rate, short process flow and the like, so that the method is expected to become an important way for reducing the manufacturing cost of the titanium and titanium alloy parts.

At present, the main methods for preparing titanium powder include a hydrogenation dehydrogenation method, an electrolytic method, a mechanical pulverization method, and an atomization method; among them, the hydrogenation dehydrogenation method for preparing titanium powder has the advantages of narrow powder particle size range, wide variety of usable raw materials, low preparation cost, easy realization of process and the like, and has become the most common method for industrially producing titanium powder. However, the titanium powder prepared by the hydrogenation and dehydrogenation method has irregular shape and poor fluidity, and is difficult to be applied to powder injection molding technologies such as laser molding and spraying.

Disclosure of Invention

The invention aims to provide a laser melting deposition method of hydrogenated titanium dehydrogenate powder to prepare a high-performance titanium part.

The technical scheme adopted by the invention for solving the technical problems is as follows: the laser melting deposition method of the hydrogenated titanium hydride powder comprises the following steps:

s1, selecting irregular hydrogenated dehydrogenated titanium powder as a raw material; spheroidizing the raw material powder by adopting a spheroidizing method;

s2, sieving the powder after spheroidizing in the step S1 by a metal powder sieve; then collecting powder with the particle size smaller than the mesh size of the metal powder sieve, putting the powder into a vacuum drying box, heating the powder to 100-150 ℃ in a vacuum environment, preserving the heat for 1-3 hours, and cooling the powder along with the box;

s3, selecting a pure titanium plate as a forming substrate, and cleaning the surface to be deposited of the forming substrate;

s4, setting laser melting deposition process parameters and a laser scanning path in the laser melting deposition system; wherein, the laser melting deposition process parameters are as follows: the laser power is 400-1000W; the scanning speed is 200-600 mm/min; the powder feeding speed is 0.8 to 1.5 rad/min; the flow rate of the inert gas is 10-20L/min; the lifting amount is 1.5-4 mm;

s5, firstly, under the protection of inert gas, putting the powder dried in the step S2 into a powder feeder of a laser melting deposition system; and then, starting a laser melting deposition system, and melting and depositing powder on the forming substrate layer by layer under the protection of inert gas according to set laser melting deposition process parameters and a scanning path to prepare the titanium part.

Further, after step S5, the method further includes: s6, the surface of the titanium member prepared in step S5 is ground and then cleaned with absolute ethyl alcohol.

Further, in step S1, the raw material powder is spheroidized by using a radio frequency plasma spheroidizing method.

Further, the feeding speed in the radio frequency plasma spheroidizing method is 20-200 g/min.

Further, in step S3, the cleaning of the surface to be deposited of the shaped substrate includes the following steps: firstly, polishing the surface to be deposited of a forming substrate; then, immersing the formed substrate in acetone, and cleaning by adopting ultrasonic waves; then, the formed substrate is placed in an inert gas for protection.

Further, the inert gas is argon.

Further, in step S4, the laser melting deposition process parameters further include: the single scanning thread is 5-300 mm.

The invention has the beneficial effects that: according to the laser melting deposition method of the hydrogenated and dehydrogenated titanium powder, different laser scanning paths can be set according to requirements, and titanium parts in different shapes can be produced; by specific laser melting deposition process parameters, the titanium part with uniform microstructure and excellent mechanical property can be prepared. The invention has high automation degree and high production efficiency, takes irregular hydrogenated and dehydrogenated titanium powder as a raw material, and has low raw material cost, thereby generating more economic benefits and having high commercial value.

Drawings

FIG. 1 is an SEM histotopography of a feedstock powder and spherical powders prepared at different feed rates;

FIGS. 2 to 4 are graphs of tensile stress strain curves of titanium members of examples and comparative examples of the present invention;

fig. 5 is a metallographic photograph of titanium members of examples and comparative examples of the present invention.

Detailed Description

The invention is further illustrated with reference to the following figures and examples.

The laser melting deposition method of the hydrogenated dehydrogenated titanium powder provided by the embodiment of the invention comprises the following steps of:

In step S1, irregular hydrogenated dehydrogenated titanium powder is selected as a raw material, and the raw material is titanium powder produced by a hydrogenated dehydrogenated method. The diagram a in fig. 1 shows the SEM texture profile of the raw material, and it can be seen that the shape of the hydrogenated titanium dehydrogenated powder is irregular. The irregular raw material powder is spheroidized by a spheroidizing method to prepare spherical powder which can be used as a raw material in powder injection molding technologies such as laser 3D printing, spraying and the like.

At present, the methods for preparing spherical metal powder mainly include: gas atomization method, plasma rotating electrode method and radio frequency plasma spheroidizing method. Compared with an air atomization method and a plasma rotating electrode method, the heat utilization rate of the radio frequency plasma spheroidizing method can reach more than 95%, the prepared spherical powder has the advantages of high sphericity, low nitrogen and oxygen content, narrow particle size range and the like, the unit price is less than one third of that of the air atomization method, and the method has more market competitiveness. Therefore, in step S1, the raw material powder is preferably spheroidized by a radio frequency plasma spheroidizing method to obtain spherical titanium powder.

The principle of the radio frequency plasma spheroidization method is as follows: the induction heating of various gases is carried out by utilizing the induction action of a radio frequency electromagnetic field to generate radio frequency plasma, the non-spherical powder is melted by utilizing the high-temperature plasma, and the melted powder particles are rapidly condensed to form small liquid drops with high spherical degree under the action of surface tension and extremely high temperature gradient, so that the spherical powder is obtained.

The embodiment of the invention adopts a radio frequency plasma powder processing system developed by TEKNA company of Canada. When the plasma torch is in work, argon is ionized under the action of a high-frequency power supply, stable high-temperature inert gas plasma is formed in the plasma torch, raw material powder with an irregular shape is sprayed into the plasma torch through a feeding gun by using nitrogen, powder particles absorb a large amount of heat in the high-temperature plasma, the surface of the powder particles is rapidly melted, the powder particles enter a heat exchange chamber at an extremely high speed, the powder particles are rapidly cooled in an inert atmosphere, the powder particles are cooled and solidified into spherical powder under the action of surface tension, and then the spherical powder particles enter a gas-solid separation chamber to be collected. Of course, the rf plasma powder processing system developed by other companies may also be used, and is not limited herein.

In the embodiment of the invention, the feeding speed in the radio frequency plasma spheroidizing method is 20-200 g/min, namely the speed of spraying the raw material powder into a plasma torch from a feeding gun is 20-200 g/min; the larger the feed rate of the raw material powder, the shorter the residence time of the powder particles in the plasma torch, resulting in a decrease in the spheroidization rate of the powder. In the embodiment of the invention, the preferable feeding speed is 30-60 g/min. FIG. 1, panel b, shows the SEM histotopography of the spherical powder prepared at a feed rate of 30g/min, FIG. 1, panel c, shows the SEM histotopography of the spherical powder prepared at a feed rate of 45g/min, and FIG. 1, panel d, shows the SEM histotopography of the spherical powder prepared at a feed rate of 60 g/min. As can be seen from the figure, the spheroidization rates of the powders are different at different feeding speeds; and the larger the feed rate, the lower the spheroidization rate and the larger the number of spherical particles having a larger particle diameter.

In step S2, the spherical powder prepared in step S1 is sieved for the purpose of: firstly, removing impurities with larger particle size and irregular shape in the powder; secondly, the powder with the particle size smaller than the mesh size of the metal powder sieve is sieved out. In the embodiment of the present invention, the spherical powder prepared in step S1 may be sieved using metal powder sieves having mesh sizes of 240 μm, 220 μm, 200 μm, 180 μm, 160 μm, 140 μm, 120 μm, 100 μm, 80 μm, 60 μm, 40 μm, 20 μm, etc., respectively. And after the screening is finished, feeding the screened powder into a vacuum drying oven for drying, specifically, heating to 100-150 ℃ in a vacuum environment, preserving heat for 1-3 h, and cooling along with the oven. By drying the spherical powder, it is possible to remove moisture in the spherical powder and reduce the oxygen content in the spherical powder.

In step S3, a pure titanium plate is selected as a forming substrate of the spherical powder at the time of laser fusion deposition, and the surface to be formed of the forming substrate is cleaned. The surface to be deposited refers to a surface for depositing a titanium part; the cleaning of the surface to be deposited of the shaped substrate comprises the following steps: firstly, polishing the surface to be deposited of a forming substrate; then, immersing the formed substrate in acetone, and cleaning by adopting ultrasonic waves; then, the formed substrate is placed in an inert gas for protection. Specifically, after cleaning of the formed substrate is completed, the formed substrate is placed in a cavity protected by inert gas in a laser melting deposition system and fixedly clamped on a turntable for standby, and the inert gas is argon.

In step S4, laser fusion deposition process parameters are set in the laser fusion deposition system, and a laser scan path is set according to the structure of the titanium part. The laser melting deposition system is a common device in powder injection molding technologies such as laser 3D printing and spraying, and has the characteristics of good molding, high bonding strength, high automation degree, customizable operation and the like. The embodiment of the present invention employs a laser melting deposition system developed by TEKNA, canada, and of course, a laser melting deposition system developed by another company may also be employed, which is not specifically limited herein. In the embodiment of the invention, the single scanning thread during laser scanning is 5-300 mm.

In step S5, under the protection of inert gas, the spherical powder in step S2 is first put into a powder feeder of a laser melting deposition system to avoid the spherical powder from changing in dryness and oxygen content due to contact with air; and then under the protection of inert gas, melting and depositing the spherical powder on a forming substrate by a laser melting and depositing system to prepare the titanium part.

After step S5, the method further includes: s6, the surface of the titanium member prepared in step S5 is ground and then cleaned with absolute ethyl alcohol. After the titanium part is cleaned, the microstructure morphology of the titanium part can be observed through an electron microscope and a scanning electron microscope.

Example 1:

s1, spheroidizing irregular hydrogenated and dehydrogenated titanium powder by a radio frequency plasma spheroidizing method, wherein the feeding speed is 30 g/min;

s2, screening the powder after spheroidizing in the step S1 by using a metal powder sieve with the sieve pore size of 180 mu m, collecting spherical powder with the particle size of less than 180 mu m, putting the spherical powder into a vacuum drying box, heating to 150 ℃ in a vacuum environment, preserving heat for 1h, and cooling along with the box;

s4, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 400W; the scanning speed is 200 mm/min; the powder feeding speed is 0.8 rad/min; the flow of argon is 10L/min; the lifting amount is 1.5 mm; the single scanning thread is 5-300 mm;

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part A1;

s6, the surface of the titanium member a1 was polished and then cleaned with absolute ethanol.

Example 2:

s2, screening the powder after spheroidizing in the step S1 by using a metal powder sieve with the sieve pore size of 120 mu m, collecting spherical powder with the particle size of less than 120 mu m, putting the spherical powder into a vacuum drying box, heating the spherical powder to 120 ℃ in a vacuum environment, preserving heat for 2 hours, and cooling the spherical powder along with the box;

s4, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 600W; the scanning speed is 400 mm/min; the powder feeding speed is 1 rad/min; the flow of argon is 15L/min; the lifting amount is 2.5 mm; the single scanning thread is 5-300 mm;

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part A2;

s6, the surface of the titanium member a2 was polished and then cleaned with absolute ethanol.

Example 3:

s2, screening the powder after spheroidizing in the step S1 by using a metal powder sieve with the sieve pore size of 80 microns, collecting spherical powder with the particle size of less than 80 microns, putting the spherical powder into a vacuum drying box, heating to 150 ℃ in a vacuum environment, preserving heat for 1 hour, and cooling along with the box;

s4, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 1000W; the scanning speed is 600 mm/min; the powder feeding speed is 1.5 rad/min; the flow rate of argon gas is 20L/min; the lifting amount is 4 mm; the single scanning thread is 5-300 mm;

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part A3;

s6, the surface of the titanium member A3 was polished and then cleaned with absolute ethanol.

Example 4:

s1, spheroidizing irregular hydrogenated and dehydrogenated titanium powder by a radio frequency plasma spheroidizing method, wherein the feeding speed is 45 g/min;

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part B1;

s6, the surface of the titanium member B1 was polished and then cleaned with absolute ethanol.

Example 5:

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part B2;

s6, the surface of the titanium member B2 was polished and then cleaned with absolute ethanol.

Example 6:

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part B3;

s6, the surface of the titanium member B3 was polished and then cleaned with absolute ethanol.

Example 7:

s1, spheroidizing irregular hydrogenated and dehydrogenated titanium powder by a radio frequency plasma spheroidizing method, wherein the feeding speed is 60 g/min;

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part C1;

s6, the surface of the titanium member C1 was polished and then cleaned with absolute ethanol.

Example 8:

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part C2;

s6, the surface of the titanium member C2 was polished and then cleaned with absolute ethanol.

Example 9:

s5, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part C3;

s6, the surface of the titanium member C3 was polished and then cleaned with absolute ethanol.

Comparative example 1:

s1, selecting irregular hydrogenated and dehydrogenated titanium powder as a raw material, putting the raw material into a vacuum drying box, heating to 150 ℃ in a vacuum environment, preserving heat for 1h, and cooling along with the box;

s2, selecting a pure titanium plate as a forming substrate, and cleaning the surface to be deposited of the forming substrate;

s3, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 400W; the scanning speed is 200 mm/min; the powder feeding speed is 0.8 rad/min; the flow of argon is 10L/min; the lifting amount is 1.5 mm; the single scanning thread is 5-300 mm;

s4, under the protection of argon, putting the hydrogenated dehydrotitanium powder in the step S1 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part D1;

s5, the surface of the titanium member D1 was polished and then cleaned with absolute ethanol.

Comparative example 2:

s1, selecting irregular hydrogenated and dehydrogenated titanium powder as a raw material, putting the raw material into a vacuum drying box, heating to 120 ℃ in a vacuum environment, preserving heat for 2 hours, and cooling along with the box;

s3, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 600W; the scanning speed is 400 mm/min; the powder feeding speed is 1 rad/min; the flow of argon is 15L/min; the lifting amount is 2.5 mm; the single scanning thread is 5-300 mm;

s4, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part D2;

s5, the surface of the titanium member D2 was polished and then cleaned with absolute ethanol.

Comparative example 3:

s3, setting laser melting deposition process parameters and a laser scanning path; wherein the laser power is 1000W; the scanning speed is 600 mm/min; the powder feeding speed is 1.5 rad/min; the flow rate of argon gas is 20L/min; the lifting amount is 4 mm; the single scanning thread is 5-300 mm;

s4, under the protection of argon, putting the spherical powder in the step S2 into a powder feeder of a laser melting deposition system; starting a laser melting deposition system, and melting and depositing powder on a forming substrate layer by layer under the protection of argon according to set laser melting deposition process parameters and a scanning path to prepare a titanium part D3;

s5, the surface of the titanium member D3 was polished and then cleaned with absolute ethanol.

Comparative example 4:

the titanium component E1, the titanium component E2 and the titanium component E3 are prepared by the existing casting method, after the preparation is completed, the surface of the titanium component is ground, and then absolute ethyl alcohol is adopted for cleaning.

By performing mechanical property tests on the titanium members in the above examples and comparative examples, the results were as follows: fig. 2 to 4 are graphs showing tensile stress strain curves of the titanium member. Wherein, the tensile stress strain curves of the titanium part A1, the titanium part B1, the titanium part C1, the titanium part D1 and the titanium part E1 are shown in FIG. 2; the tensile stress strain curves for titanium part A2, titanium part B2, titanium part C2, titanium part D2, and titanium part E2 are shown in FIG. 3; the tensile stress strain curves for titanium part A3, titanium part B3, titanium part C3, titanium part D3, and titanium part E3 are shown in FIG. 4.

The mechanical property test results of the titanium parts in the examples and comparative examples of the present invention are shown in the following table:

as can be seen from the above table, the elongation of the titanium part prepared by the method of the present invention is not less than 15%, which meets the practical application requirements at the present stage, but has higher tensile strength and yield strength. Therefore, compared with the prior art, the method can prepare the titanium part with higher strength under the condition of ensuring the plasticity of the titanium part to be at the same level.

By observing the surfaces of the titanium members in the above examples and comparative examples, the results are shown in fig. 5.

FIG. 5, panel a, FIG. 5, is a metallographic picture of titanium part A1, FIG. 5, panel b, FIG. 5, is a metallographic picture of titanium part A2, and FIG. 5, panel c, is a metallographic picture of titanium part A3;

FIG. d of FIG. 5 is a metallographic photograph of a titanium part B1, FIG. e of FIG. 5 is a metallographic photograph of a titanium part B2, and FIG. f of FIG. 5 is a metallographic photograph of a titanium part B3;

fig. g in fig. 5 is a metallographic photograph of a titanium part C1, fig. h in fig. 5 is a metallographic photograph of a titanium part C2, and fig. i in fig. 5 is a metallographic photograph of a titanium part C3;

FIG. j of FIG. 5 is a photomicrograph of the titanium part D1, FIG. k of FIG. 5 is a photomicrograph of the titanium part D2, and FIG. l of FIG. 5 is a photomicrograph of the titanium part D3;

fig. m in fig. 5 is a metallographic photograph of the titanium part E1, fig. n in fig. 5 is a metallographic photograph of the titanium part E2, and fig. o in fig. 5 is a metallographic photograph of the titanium part E3.

As can be seen from the graphs m, n and o in FIG. 5, the titanium component prepared by the casting method has a typical equiaxial alpha-phase structure and the grain size is about 30-50 μm. As can be seen from the graphs j, k and l in FIG. 5, the laser melting deposition structure of the titanium powder without spheroidizing treatment has many holes, which is caused by the phenomenon that the flowability of the titanium powder without spheroidizing is poor, so that the powder flow efficiency is low in the laser melting deposition process and the powder feeding is discontinuous, thereby generating pores.

As can be seen from the graphs a to i in FIG. 5, the titanium part prepared by the method of the present invention has the advantages of obviously reduced internal defects, uniform grain size of about 200 to 300 μm, irregular grain of the sample structure after laser melting deposition due to the influence of the laser scanning strategy and the unbalanced preparation process, and saw-toothed grain boundary, which is one of the reasons that the sample deposited by laser melting has higher tensile strength and lower elongation than the cast sample.

According to the laser melting deposition method of the hydrogenated and dehydrogenated titanium powder, different laser scanning paths can be set according to requirements, and titanium parts in different shapes can be produced; by specific laser melting deposition process parameters, the titanium part with uniform microstructure and excellent mechanical property can be prepared. The invention has high automation degree and high production efficiency, takes irregular hydrogenated and dehydrogenated titanium powder as a raw material, has no specific requirement on the raw material, has low raw material cost, can generate more economic benefits and has high commercial value.

Claims

1. The laser melting deposition method of the hydrogenated titanium hydride powder is characterized by comprising the following steps:

2. The laser fusion deposition method of hydrogenated titanium dehydrogenate powder of claim 1, further comprising, after step S5: s6, the surface of the titanium member prepared in step S5 is ground and then cleaned with absolute ethyl alcohol.

3. The laser fusion deposition method of hydrogenated titanium dehydrogenated powder according to claim 1 or 2, wherein in step S1, the raw material powder is spheroidized by radio frequency plasma spheroidizing.

4. The laser melting deposition method of hydrogenated titanium dehydrogenated powder according to claim 3, wherein the feeding speed in the radio frequency plasma spheroidizing method is 20 to 200 g/min.

5. The laser fusion deposition method of hydrogenated titanium dehydrogenated powder as claimed in claim 1, wherein the cleaning of the surface to be deposited of the shaped substrate in step S3 comprises the steps of: firstly, polishing the surface to be deposited of a forming substrate; then, immersing the formed substrate in acetone, and cleaning by adopting ultrasonic waves; then, the formed substrate is placed in an inert gas for protection.

6. The method for laser fusion deposition of hydrogenated titanium dehydrogenate powder according to claim 1, wherein the inert gas is argon.

7. The method of claim 1, wherein in step S4, the laser fusion deposition process parameters further include: the single scanning thread is 5-300 mm.